It is well known that a thermal sensor such as a thermal switch is used in a heat generating device as an electric heater. The thermal sensor works as a safety device to sense a temperature increase exceeding a certain temperature to stop the operation of a heat generating device or generate an anomaly detecting signal, for example.
Such a thermal sensor uses a thermally deformable bimetal inside (see Patent Literature 1, for example).
The thermal sensor includes a case with an aperture and a cover member occluding the aperture, in which the edge or periphery of the bimetal is placed in-between the case and the cover member to hold the bimetal, for example.